Mercury switch activated by any mechanical means



Oct. 11, 1966 H. B. ACKERMAN MERCURY SWITCH ACTIVATED BY ANY MECHANICAL MEANS Filed NOV. 19, l964 United States Patent Office 3,273,703 Patented Oct. 11, 1966 3,278,703 MERCURY SWITCH ACTIVATED BY ANY MECHANICAL MEANS Howard B. Ackerman, 126 William Road, Massapequa, N.Y. Filed Nov. 19, 1964, Ser. No. 412,384 Claims. (Cl. 200-81.8)

This invention relates to electrical switches and more particularly to mercury switches.

Mercury switches are known that comprise a glass vial mounted to be rocked about a horizontal axis. At one end of the vial are two silver contacts exposed within the vial and a pool of mercury that, tilting the vial in one direction, submerges the silver contacts in mercury by causing the mercury to run to that end of the container at which the contacts are provided to complete the circuit, and tilting the vial in the other direction causes the mercury to flow away from the contacts to break the circuit between the two contacts. The contacts are provided with leads extending through the glass and are connected by flexible connections to an electric circuit.

It is an object of the present invention to provide a better mercury switch.

The price of mercury switches has been high as the glass vials are expensive and there are difficulties in providing leads through the glass. The material of the leads, and of the vial, under the present invention have been radically changed, and the design of the switch has been modified to reduce the cost of the switch by using less expensive materials and simpler manufacturing techniques, while at the same time, providing a mercury switch capable of carrying larger electrical loads.

It is, therefore, a further object of the present invention to provide a mercury switch that is inexpensive to manufacture and which will be useful for high current uses.

.Other and further objects and advantages will become apparent from the following specification taken with the accompanying drawing in which like characters of reference refer to similar parts in the several views and in which FIGURE 1 is an elevation of the device;

FIGURE 2 is a view looking upwardly at the structure as shown in FIGURE 1;

FIGURE 3 is a fragmentary side elevation showing a detail of the device; and

FIGURE 4 is a section on line 44 of FIGURE 1.

In FIGURES 1, 2 and 3 there is shown a support plate 1, on which an adjusting lever 2 is pivoted at 3. A scale 4 may be provided to indicate the positioned lever 2.

A thermo-responsive element 5, which in this example, is shown as a Bourdon tube sealed at each end and enclosing a volatile liquid such, for example, as ether, so that upon a rise in temperature the tube tends to straighten out, and upon cooling the tube tends to curl into a smaller arc, is secured by one end to adjusting lever 2. Clearly, materials other than ether may be used within the tube 5 depending on the temperature range over which the device is to be used. A bimetallic element could be used at 5, but the Bourdon tube is preferred.

The other end of Bourdon tube 5 is operatively connected by a link 6 to a segment gear 7 that is pivotally mounted on plate 1 near pivot 3. A gear 8 is rotatably mounted on pivot 3 that works with segment gear 7 to be rotated thereby. Shaft 9, fixed to gear 8, carries an actuator 10, that will 'be moved about pivot 3 under the influence of Bourdon tube 5 acting through link 6, segment gear 7 and pinion 8. The adjusted position of actuator 10 is set by lever 2 positioning tube 5, and the actuator departs from its set position under the influence of changes of curvature of tube 5 under the influence of changes of temperature.

Mercury switch 11 is pivoted on support arms 12, 12' that are positioned to hold the switch for rocking about a horizontal axis located approximately on the line bisecting the angle through which actuating blade 10 is designed to swing.

Spring contact element 13 is held on support 12 and spring contact element 13 is held on support 12', terminals 14 and 14' are provided, by which leads for the circuit to be controlled may be connected to the switch.

Switch 11 is formed of molded plastic. Container 15, which is the body of the switch, has two separate compartments 16 and 17, compartment 16 being preferably slightly more than half the length of the container 15. Containers 16 and 17 may each be provided with a sealable opening through which mercury may be introduced so it is not necessary to insert the mercury until all other steps of the manufacture of the switch 11 have been performed.

The pivots 18, 18 by which switch 11 is mounted on supports 12, 12', are formed of magnets which may be of a material known as Alnico or of other strongly magnetic material. These magnetic pivots 18, 18' also constitute the contacts within the chamber 16. The area of contacts 18, 18' is large, and, therefore, their resistance to the flow of electricity is small. The electrical resistance of mercury is also small so that the heating of the switch by the flow of electricity will be minimal.

The magnetic contact pivots 18 are electrically connected by spring elements 13, 13 to terminal posts 14, 14. Springs 13, 13' also position the container portion 15 of the switch between support arms 12, 12'.

Pivots 18, 18 are pressed into the apertures in container 15, and, if desired, the mercury may be inserted into container 15 through the aperture into which pivot 18 is to be inserted.

It is contemplated that the compartment 17 of the switch 11 be partially filled with mercury or other fluid material to provide a movable counterweight for the mercury in the compartment 16. While a fixed counterweight could be used, the fluid or movable counterweight, being able to move from end to end of compartment 17, gives, in effect, a snap action to the switch since once the container is horizontal, the counterweight as well as the mercury in compartment 16, will move in the direction of tilt.

Extending upwardly from opposite ends of the switch 11 are two elements 19 and 20. Adjusting screws 21 and 22 extend parallel to the length of container 15 and are positioned so that the actuator blade 10 lies between them. While the screws 21 and 22 may be adjusted so that the container 15 follows the movement of blade 10 closely, it is contemplated that the ends of the screws 21 and 22 be normally spaced apart so that when the actuating blade 10 pressing on one or other of the adjusting screws pivots the container into horizontal position in either direction, the container will be forced to pivot further in that direction under the influence of the movement of the mercury in the compartment 16 and counterweight in compartment 17.

It will be noted from FIGURE 1 that at the setting shown 65 the switch 11 has been tilted so that current is flowing from terminals 14, 14' through springs 13, 13', contact pivot elements 18, 18' and through the mercury within compartment 16. Assuring the switch is being used as a control for a heating system, as the Bourdon tube 5 is heated, it tends to straighten, so will pull on link 6 which will turn segmented gear 7 on its pivot in a counterclockwise direction, and so gear 8 and actuator blade 10 will be pivoted in clockwise direction until blade 10 contacts adjusting screw 21 and rocks switch 11 in an anticlockwise direction to break the connection of the mercury with magnetic contacts 18, 18'.

Assuming the switch, set at 65, has been actuated so that current flows through the switch because it is tilted so that mercury in compartment 16 is in contact with contacts 18, 18', as is the case in FIGURE 1, if then the lever 2 is moved to the right, the tube 5 is moved counterclockwise which will pull link 6 which will pivot segment gear 7 counterclockwise, which will rotate pinion 8, and therefore actuator blade 10, in the clockwise direction which in turn will contact screw stop 21 to tilt the switch 11 to break the circuit.

It is seen, then, that lever 2 may be set at any point on scale 4 as a datum from which switch 11 will operate, the Bourdon tube 5 containing a material having a large variation of vapor pressure per degree change of temperature, and being flexible, will have a large change of dimension compared to a small change of temperature, so that the movement of the actuator blade will be relatively large for a small change of temperature to give a close control of the switch 11. The gear ratio between segment 7 and gear 8 may, of course, be selected as required.

The action of switch 11 will be quick both in the circuit making direction and in the circuit breaking direction since the moment the container 15 is pivoted past the horizontal, both the mercury in compartment 16 and the counterweight in compartment 17 will move, giving a sudden movement of the center of gravity across the axis of pivots 18, 18' so that the container 15 snaps over into the desired position. The quick motion of the switch, the large area of contacts 18, 18' and the fact that the contacts 18, 18' are magnets, that prevent arcing between the elements 18, 18, holds the heating of the switch to a minimum.

It will be seen, therefore, that the present invention provides a single, inexpensive, highly responsive switch.

Having thus described the invention, what I claim is:

1. A switch comprising a base plate, an adjusting lever pivotally mounted on said base plate, a temperature responsive element mounted on said lever having one end extending to a position radially remote from the pivot of said lever, a link secured by one end to said one end of said temperature responsive element, a segment gear pivotally mounted on said base plate, said segment gear being operatively connected to the other end of said link so as to be pivoted by movement of said one end of said temperature responsive element, a pinion mounted on said base plate coaxially of said adjusting lever meshing with said segment gear, a switch actuator blade fixed for movement with said pinion extending radially from the axis thereof, a mercury switch pivotally mounted on a horizontal pivot on said base plate so that upon tilting in one direction an electrical connection is made, and upon tilting in the other direction, the electrical connection is broken, said actuating blade being operatively connected to said mercury switch to cause said switch to be tilted due to movement of said actuator blade upon movement of said adjusting lever or upon change of shape of said tem perature responsive element upon a change of temperature.

2. A mercury switch comprising a receptacle providing a compartment having a bottom, mercury in said compartment to lie on the bottom thereof, pivot means adapted to lie in a horizontal plane on which said receptacle is mounted, whereby said receptacle may be tilted to cause the bottom of said compartment to slope in one or the other direction, said pivot means being located near one end of said compartment and being formed of two magnets extending from without to within said compartment to form contacts engageable by said mercury and to provide gudgeons on which said receptacle pivots, contact means engaging the exterior ends of said magnets, contact terminals on said contact means whereby said switch may be connected in an electric circuit, and means to selectively tilt said receptacle.

3. The switch of claim 2 in which said receptaclei's of synthetic resin.

4. The switch of claim 3 in which said magnets forming the gudgeons are press fitted into the walls of said receptacle.

5. The switch of claim 2 in which a counterweight is provided, a second compartment being provided in said receptacle separate from the compartment containing the mercury, and a fluid counterweight material movably contained in said compartment whereby, upon tilting of said receptacle the said counterweight will move in the direction of tilt.

References Cited by the Examiner UNITED STATES PATENTS 6/1930 Thommes 200- X 6/1956 Foster 20081.8 X 

1. A SWITCH COMPRISING A BASE PLATE, AN ADJUSTING LEVER PIVOTALLY MOUNTED ON SAID BASE PLATE, A TEMPERATURE RESPONSIVE ELEMENT MOUNTED ON SAID LEVER HAVING ONE END EXTENDING TO A POSITION RADIALLY REMOTE FROM THE PIVOT OF SAID LEVER, A LINK SECURED BY ONE END TO SAID ONE END OF SAID TEMPERATURE RESPONSIVE ELEMENT, SEGMENT GEAR PIVOTALLY MOUNTED ON SAID BASE PLATE, SAID SEGMENT GEAR BEING OPERATIVELY CONNECTED TO THE OTHER END OF SAID LINK SO AS TO BE PIVOTED BY MOVEMENT OF SAID ONE END OF SAID TEMPERATURE RESPONSIVE ELEMENT, A PINION MOUNTED ON SAID BASE PLATE COAXIALLY OF SAID AJUSTING LEVER MESHING WITH SAID SEGMENT GEAR, A SWITCH ACTUATOR BLADE FIXED FOR MOVEMENT WITH SAID PINION EXTENDING RADIALLY FROM THE AXIS THEREOF, A MERCURY SWITCH PIVOTALLY MOUNTED ON A HORIZONTAL PIVOT ON SAID BASE PLATE SO THAT UPON TILTING IN ONE DIRECTION AN ELECTRICAL CONNECTION IS MADE, AND UPON TILTING IN THE OTHER DIRECTION, THE ELECTRICAL CONNECTION IS BROKEN, SAID ACTUATING BLADE BEING OPERATIVELY CONNECTED TO MERCURY SWTICH TO CAUSE SAID SWITCH TO BE TILTED DUE TO MOVEMENT OF SAID ACTUATOR BLADE UPON MOVEMENT OF SAID ADJUSTING LEVER OR UPON CHANGE OF SHAPE OF SAID TEMPERATURE RESPONSIVE ELEMENT UPON A CHANGE OF TEMPERATURE. 